Currently the liquid crystal displays (LCDs) have been dominating in almost all the major display markets for several applications, such as monitors, mobile phones, televisions, notebook computers, tablet personal computers (PCs), global positioning system (GPS) devices, portable video players, as the technologies of the LCD have been developing widely, deeply and quickly.
The liquid crystals play the role of light valves to control the light transmission and the light blocking at instantaneous display time in each pixel of the LCD. In the view of the control mechanisms of the liquid crystals, the LCD can be divided into the types of the vertical alignment (VA) and the plane switching.
The VA type can be further divided into several sub-types. Generally, the VA type LCD has very fast response time for the liquid crystals, and is especially suitable for displaying the video showing very fast movements. However, when the user presses the LCD screen by fingers or other objects, the vortex-shaped pattern appears at the place being pressed on the screen of the LCD, because the distance interval of the vertical alignment of the liquid crystals is shortened by such vertically pressing on the screen. In this aspect, the VA LCD is not suitable to be used for the touch-panel display, since the screen of the touch-panel display tends to be frequently touched and pressed by the user's finger, and the displayed picture thereof will be blurred at anywhere is being touched.
On the other hand, the plane switching type LCDs, including the in-plane switching (IPS) and the fringe field switching (FFS) LCDs, do not have this kind of problem, and provide good performance for the touch-panel display, since the liquid crystal alignments thereof occur in the plane (horizontal) direction rather than the vertical direction. Generally, FFS LCD has larger aperture ratio and transmittance than those of IPS LCD, and makes itself as a good candidate for the portable touch-panel display. However, the charging time for the counter electrode in each pixel of the typical FFS LCD is not short enough, and results in the long response time.
Refer to FIG. 1A, which shows a top view of a pixel in a conventional FFS LCD of the prior art. In FIG. 1A, the pixel electrode 11 includes plural slits 111 and plural strips 112, while the counter electrode 12 is a plane electrode. The pixel electrode 11 is disposed right above the counter electrode 12, where the electrical field directions in this pixel from the top view are shown by arrows, and are usually from the slits 111 to the strips 112, that is, the transverse directions, from right to left or form left to right. FIG. 1B shows a cross section view of the pixel in FIG. 1A along dash line A-A, where the electrical field directions from this cross section view are shown by arrows. Basically, the pixel electrode 11 can be positively or negatively charged. The pixel electrode is positively charged, when the counter electrode is negatively charged, and vice versa, so as to create the electrical fields. FIG. 1C is an enlarged view on the area encircled by the dash line in FIG. 1A. It can be seen from FIG. 1C that the electrical field directions at the ends of the slits are no longer in the transverse directions shown in FIG. 1A due to the top boundary of the pixel electrode 11, since the electrical field is created from the positively charged area, e.g. counter electrode 12, to the negatively charged area, e.g. pixel electrode 11, which includes several strips 112 and top and bottom boundaries. This non-uniformity of the electrical fields on the two ends of each slit causes the dark lines (dark stripes) at each end of the slits when the pixel is in turn-on condition. This problem results in lowering the maximum brightness and the contrast ratio, and consequently energy waste and poor displayer performance.
For overcoming the above-mentioned problem existing in the conventional techniques, the novel FFS LCD apparatuses are provided in the present invention to solve the above problem and to provide excellent display performance.